Influence of Various Rotor Pole on Electromagnetic Performance of Consequent Pole Switched Flux Permanent Magnet Machine

Abstract

Switched Flux Permanent Magnet Machines (SFPMM) exhibit pivotal role in high speed applications when high torque and power density are essential requirements. However, existing conventional SFPMM utilizes more Permanent Magnet (PM) volume results in overall increase of machine cost and weight. Moreover, high PM usage enhance interaction with rotor core that ultimately generate cogging torque (no load torque) which introduce vibration and acoustic noise. In additional, conventional SFPMM exhibits flux leakages from the PMs end which effects electromagnetic performance. In this paper, a novel consequent pole SFPMM (CPSFPMM) with flux bridges, flux barriers and reduced partition PMs is introduced which leads in reduction of total machine cost, weight and decrease of the cogging torque. Moreover, rotor pole analysis is carried out for optimal combination of the rotor poles number combination for initial optimal design of CPSFPMM with key performance indicators such as open-circuit flux linkage, cogging torque, mechanical torque, Total harmonic distortion (THD), torque ripple ratio, average torque and average power characteristics. Based on Finite Element Analysis (FEA) on commercial FEA package JMAG v. 14, CPSFPMM with 12-stator slot and 13 rotor poles is searched out to be optimal design with comparatively best electromagnetic performance. Moreover, proposed novel CPSFPMM is compared with existing conventional SFPMM. Analysis reveals that proposed CPSFPMM utilized 77% PM volume, which reduce machine cost, weight, and offer 124.06% peak to peak open-circuit flux linkage, 52.74% peak to peak cogging torque, 99.2% average torque, 34.67% THD and 77.64% torque ripple ratio when compared with existing conventional SFPMM.